Chapter 10
Configuring the System Clock
Use the procedures described in this chapter to configure the E Series router clock.
This chapter contains the following sections:
â– Overview on page 521
â– Platform Considerations on page 524
â– References on page 524
â– Setting the System Clock Manually on page 525
â– Before You Configure NTP on page 527
â– NTP Configuration Tasks on page 527
â– Monitoring NTP on page 533
Overview
You can use the clock commands to set the time and date on your system manually.
These commands allow you to specify settings such as the source of the time, the
time zone, and dates for seasonal time changes.
You can configure your router to update its clock automatically by configuring it as
a Network Time Protocol (NTP) client. NTP provides a method of synchronizing the
system clocks of hosts on the Internet to Universal Coordinated Time (UTC). Using
NTP allows the system to record accurate times of events. You can view the log file
of events to monitor the status of the network.
Since there is only one system clock, you can configure an NTP client on one virtual
router only. Other virtual routers obtain clock parameters from the system clock.
However, multiple virtual routers can act as NTP servers.
NTP
NTP uses a hierarchical structure of hosts, such as computers and routers, that form
client-server and peer associations. An NTP client synchronizes with an NTP server,
which in turn synchronizes with another time source. If two hosts provide
synchronization for each other, they are peers.
Primary or stratum 1 servers synchronize directly with an accurate time source, such
as a radio clock or an atomic clock. Secondary or stratum n servers synchronize with
other servers, and are n hops from an accurate time source.
Overview â– 521